High nitrate levels in water can be particularly harmful to which group?

High nitrate levels in water are particularly harmful to infants due to a condition known as methemoglobinemia, or "blue baby syndrome." In infants, the ingestion of nitrates can interfere with the oxygen-carrying capacity of hemoglobin in the blood. When nitrates are converted to nitrites in the gastrointestinal tract, they can bind to hemoglobin and form methemoglobin, which does not effectively transport oxygen. This can lead to serious health issues, including cyanosis, which is a bluish discoloration of the skin due to inadequate oxygen levels in the blood.

Infants under six months of age are especially vulnerable because their digestive systems are more prone to converting nitrates into nitrites. Other groups, such as adults and pregnant women, can have elevated nitrate levels in their bodies, but the physiological effects and the consequent health risks are not as acute as those experienced by infants. Nitrate exposure in pregnant women may also raise concerns regarding fetal health, but the direct and immediate danger associated with high levels of nitrates primarily affects infants. Therefore, understanding these dynamics reinforces why monitoring nitrate levels in drinking water is crucial, especially in areas where such contamination could occur.